UWB信道matlab模型

% File: multipath_sim.m % Matlab Simulink IEEE 802.15.3a compliant channel model % Author: Tim Becker (MSEE Degree, December 2004) % Advisor: Robert Morelos-Zaragoza. San Jose State University function [sys,x0,str,ts] = multipath_sim(t,x,u,flag,T,nT,LAMBDA,lambda,GAMMA,gamma,sigma1_dB,sigma2_dB,std_shadow,LOSflag) % Differs from multipath_sim2.m in that h begins at t=0 for NLOS channels. v = 10000; switch flag, % Initialization case 0, [sys,x0,str,ts]=mdlInitializeSizes(T,nT,v); % Outputs case 3, sys=mdlOutputs(t,x,u,T,LAMBDA,lambda,GAMMA,gamma,sigma1_dB,sigma2_dB,std_shadow,LOSflag,v); % Unhandled flags case {1, 2, 4, 9} sys = []; % Unexpected flags otherwise error(['Unhandled flag = ',num2str(flag)]); end % end multipath_sim %============================================================================= % mdlInitializeSizes % Return the sizes, initial conditions, and sample times for the S-function. %============================================================================= function [sys,x0,str,ts]=mdlInitializeSizes(T,nT,v) sizes = simsizes; sizes.NumContStates = 0; sizes.NumDiscStates = 0; sizes.NumOutputs = v; sizes.NumInputs = 0; sizes.DirFeedthrough = 0; sizes.NumSampleTimes = 1; % at least one sample time is needed sys = simsizes(sizes); % initialize the initial conditions x0 = []; % str is always an empty matrix str = []; % initialize the array of sample times ts = [T*nT*1e-9 0]; % end mdlInitializeSizes %============================================================================= % mdlOutputs % Return the block outputs. %============================================================================= function sys=mdlOutputs(t,x,u,T,LAMBDA,lambda,GAMMA,gamma,sigma1_dB,sigma2_dB,std_shadow,LOSflag,v) % returns the real impulse response of the % indoor multipath channel as modeled by Intel in % IEEE 802.15-02/279r0-SG3a and is based on the % Saleh-Valenzuela model with lognormal fading. % T is the time resolution (nsec). sigma1 = 10^(sigma1_dB/20); sigma2 = 10^(sigma2_dB/20); Omega0 = 1; if (strcmp(LOSflag,'on')) T1 = [0]; else T1 = [randn^2/(2*LAMBDA)+randn^2/(2*LAMBDA)]; end while T1(end) <= 10*GAMMA dT = randn^2/(2*LAMBDA)+randn^2/(2*LAMBDA); T1 = [T1 T1(end)+dT]; end for n = 1:length(T1) tau(n) = {[T1(n)]}; while tau{n}(end) <= tau{n}(1)+10*gamma dt = randn^2/(2*lambda)+randn^2/(2*lambda); tau(n) = {[tau{n} tau{n}(end)+dt]}; end mu(n) = {(10*log(Omega0)-10*T1(n)/GAMMA-10*(tau{n}-T1(n))/gamma)/log(10)-(sigma1^2+sigma2^2)*log(10)/20}; beta(n) = {10.^((sigma1*randn(size(mu{n}))+sigma2*randn(size(mu{n}))+mu{n})/20)}; alpha(n) = {beta{n}.*sign(rand(size(beta{n}))-0.5)}; % Intel version, +/-1 %alpha(n) = {beta{n}.*exp(-j*2*pi*rand(size(beta{n})))}; % cell array of channel coefficients end maxtime = max(tau{1}); % find maximum arrival time index in cell array tau for n = 2:length(T1) if max(tau{n}) > maxtime maxtime = max(tau{n}); end end N = 32; % oversampling factor Nfs = N/T; h = zeros(1,floor(maxtime*Nfs)+1); % initialize impulse response vector for n = 1:length(T1) tauN{n} = floor(tau{n}*Nfs); % quantized time indices end for n = 1:length(T1) for m = 1:length(tau{n}) h(tauN{n}(m)+1-tauN{1}(1)) = h(tauN{n}(m)+1-tauN{1}(1))+alpha{n}(m); % only line different from multipath_sim2.m end end h = N*resample(h,1,N); maxtime = ceil((10*GAMMA+10*gamma)/T); % maximum arrival time for channel h = h(1:maxtime); % concatenate h to maximum channel length E = sum(h.*conj(h)); % compute total channel energy h = h./sqrt(E); % normalize total energy to 1 fac = 10^(std_shadow*randn/20); h = h.*fac; if(length(h)<v) h = [h zeros(1,v-length(h))]; elseif(length(h)>v) h = h(1:v); end %length(h) sys = real(h); % end mdlOutputs